Conventional rotorcrafts such as helicopters use exposed main rotors to generate lift and forward thrust. By tilting the main rotor to the front, back, or side-to-side the helicopter can change direction and maneuver to the desired position. However, the main rotor is also a source of the majority of the aerodynamic drag experienced by the helicopter in forward flight. In fact, the aerodynamic drag is so great that the fastest helicopters available today can only achieve a small fraction of the speed of an ordinary fixed wing aircraft. For example, the world record for the fastest helicopter is held by the Westland Lynx which achieved a speed of 249.9 miles per hour (mph). In comparison, even a small propeller powered aircraft such as the TBM 900 can cruise at a speed of 378 mph. The sluggish speed of helicopters is made even more apparent when one considers that most conventional helicopters achieve nowhere near the speed of the Lynx. For most helicopters, the aerodynamic drag produced by the rotors is so great that most helicopters travel at speeds which would cause most commercial jetliners to stall.
It is therefore the object of the present invention to provide a propulsion system enabling the same omni-directional maneuvering capability of the helicopter while reducing or eliminating the massive aerodynamic drag created by the main rotor of the helicopter. It is yet another object of the present invention to package the propulsion system as compactly as possible to reduce the cross-section impinging on the oncoming airflow and creating aerodynamic drag. It is yet another object of the present invention to eliminate the yaw moment experienced by conventional helicopter without the use of a tail rotor. Instead, the propulsion system utilizes counter-rotating rotors to cancel out the yaw moment generated by each individual rotor.
Using the propulsion system, the present invention can maneuver just like a conventional helicopter. For example, the propulsion system generates full thrust irrespective of the airspeed, thereby allowing the present invention to take off vertically and hover in place. The propulsion system also allows the present invention to tilt about the roll or yaw axis to translate sideways, forwards, and back.